JP6474336B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to a configuration of a fixing device thereof.

  Conventionally, as a fixing device of an image forming apparatus, there is an apparatus that fixes a developer image on a print medium by heating and pressurizing the medium onto which the developer image is transferred. (For example, refer to Patent Document 1).

Japanese Patent Laying-Open No. 2015-87624 (page 7, FIG. 1)

  However, in the conventional configuration, when the print medium is stopped inside the fixing device, heat is applied to the medium for a long time, which is not preferable.

The fixing device according to the present invention includes a first unit, a second unit movably arranged with respect to the first unit, and the second unit, the first unit with respect to the first unit. And a moving mechanism that slides to the second position,
The first unit includes an endless first belt, and a fixing roller rotatably held around a rotation shaft whose position is fixed inside the first belt.
The second unit includes an endless second belt, a pressure roller rotatably held around a rotation shaft displaceable inside the second belt, and the pressure roller as the fixing roller. A first urging member that urges toward the
The pressure roller is urged by the first urging member at the first position to press the fixing roller via the first belt and the second belt, and the second roller The position is separated from the fixing roller.

  According to the present invention, it is possible to form a nip portion by fixing and a pressure roller as needed, and to separate them, so that it is inconvenient that heat is applied to the recording medium for a long time. Can be avoided.

1 is a main part configuration diagram illustrating a main part configuration of a printer according to a first embodiment of an image forming apparatus including a fixing device according to the present invention; 1 is an external perspective view of a fixing device. FIG. 3 is a front view of the fixing device as viewed from the upstream side in the paper conveyance direction (arrow A direction). FIG. 3 is a front view of the fixing device with an exterior cover removed. FIG. 3 is an external perspective view of the fixing device with an exterior cover removed. FIG. 3 is a right side view of the fixing device with an exterior cover removed. It is the right view which removed the drive transmission system. It is the figure which looked at the AA cross section in FIG. 3 from the arrow direction. FIG. 4 is an exploded side view showing the upper fixed unit, the lower movable unit, and the base unit constituting the fixing device in a state of being separated from each other, (a) is a right side view of the upper fixed unit, and (b) is a lower movable unit. A right side view, (c) is a right side view of the base unit. It is an external appearance perspective view of an upper fixing unit. FIG. 11 is an external perspective view in which a drive transmission system including a fixing roller driving input gear is removed from the state of FIG. 10. FIG. 10 is a right side view of the upper fixing unit with the sub-chassis of the drive transmission system removed from the state of FIG. It is an external appearance perspective view of a lower movable unit. It is an external appearance perspective view of a base unit. It is a front view of a base unit. It is the figure which looked at the FF cross section in FIG. 15 from the arrow direction. 5 is a cross-sectional view taken along the line B-B in FIG. 4, which is a front view of the fixing device with an outer cover removed. FIG. 5 is a cross-sectional view taken along the line CC in FIG. 4, which is a front view of the fixing device with an exterior cover removed, viewed from the direction of an arrow. FIG. 6 is a view of a DD cross section in FIG. 4 as viewed from the direction of an arrow, which is a front view of the fixing device with an exterior cover removed. FIG. 5 is a cross-sectional view taken along the line E-E in FIG. 4, which is a front view of the fixing device with an exterior cover removed, viewed from the direction of an arrow. It is the figure which looked at the BB cross section in FIG. 4 from the arrow direction, Comprising: The state which the lower movable unit slid to the lowest position by the cam mechanism is shown. It is the figure which looked at the EE cross section in FIG. 4 from the arrow direction, Comprising: The state which the lower movable unit slid to the lowest position by the cam mechanism is shown. It is the external appearance perspective view which looked at the part of the arm of the right and left holding a pressure roller and a pressure roller from diagonally upward. It is an external appearance perspective view of a pressure pad and the pressure pad holder holding this. It is a block diagram which shows a position detection mechanism roughly. FIG. 2 is a block diagram illustrating a configuration of a main part of a control system that is disposed inside the printer and controls the operation of the main part of the printer.

Embodiment 1 FIG.
FIG. 1 is a main part configuration diagram showing a main part configuration of a printer according to a first embodiment of an image forming apparatus provided with a fixing device according to the present invention. The printer 1 is an electrophotographic color printer compatible with continuous printing paper.

  As shown in FIG. 1, the printer 1 includes a paper holder 4 that holds the roll paper 5, an introduction guide unit 2 that serves as an introduction unit for the roll paper 5, and a printing unit 3 that executes printing on a recording medium.

  For example, the paper holder 4 rotatably holds the axis of the roll paper 5, and rotates in response to the leading end of the roll paper 5 being pulled by the introduction guide portion 2, so that the roll paper 5 continues to the introduction guide portion 2. To supply.

  The introduction guide unit 2 is arranged in the conveyance path of the roll paper 5, the guide roller 21 that guides the conveyance of the roll paper 5, and the feed roller pair 22 that conveys the roll paper 5 downstream, in the conveyance direction of the roll paper 5. A sheet cutting unit 23 disposed on the downstream side of the pair of feed rollers 22 and a sheet sensor 24 disposed on the downstream side of the sheet cutting unit 23, and conveying and cutting the roll paper 5 at a predetermined timing; The paper sensor 24 detects the presence or absence of cut roll paper (hereinafter referred to as recording paper 6) to be sent to the printing unit 3.

  On the conveyance path of the recording paper 6 in the printing unit 3, a pair of conveyance rollers 35 and 36 that convey the recording paper 6 to the secondary transfer unit 50 from the upstream side in the direction of arrow A that is the conveyance direction of the recording paper 6, image formation A write sensor 40 for taking a write timing in the unit 30 is provided.

  The image forming unit 30 of the printing unit 3 includes four process units 31Y, 31M, 31C, and 31K that respectively form yellow (Y), magenta (M), cyan (C), and black (K) toner images. (If there is no need to distinguish between them, the reference numeral 31 is simply attached.) These indicate arrows indicating the moving direction in which the intermediate transfer belt 41 of the intermediate transfer belt unit 32 described later moves above the intermediate transfer belt unit 32. Arranged in order from the upstream side along the B direction.

  The intermediate transfer belt unit 32 of the printing unit 3 includes a drive roller 42 driven by a drive unit (not shown), a tension roller 43 that applies tension to the intermediate transfer belt 41 by a biasing means such as a coil spring, and a secondary transfer roller 34. And a secondary transfer backup roller 44 that constitutes the secondary transfer unit 50 and an intermediate transfer belt 41 that is stretched around these rollers, and further, faces the photosensitive drum 33 of each process unit 31. And four primary transfer rollers 45 for applying a predetermined voltage to sequentially transfer the color toner images formed on the photosensitive drums 33 onto the intermediate transfer belt 41.

  As described above, the intermediate transfer belt unit 32 primarily superimposes the toner images of the respective colors formed by the image forming unit 10 on the intermediate transfer belt 41 to perform primary transfer, and then secondary-transfers the primary transferred toner image. It conveys to the part 50. In the secondary transfer unit 50, the toner image primarily transferred to the intermediate transfer belt 41 is supplied to the recording paper 6 fed from the introduction guide unit 2 and conveyed by the secondary transfer roller 34 to which a predetermined voltage is applied. Transcript. For this reason, the recording paper 6 is skewed while passing through the pair of conveyance rollers 35 and 36 and the writing sensor 40, and the conveyance timing is measured.

  The fixing device 37 of the printing unit 3 includes a fixing unit 210 and a pressure unit 310 inside, and applies heat and pressure to the toner image on the recording paper 6 fed from the secondary transfer unit 50 to melt it. Then, it is fixed on the recording paper 6. Thereafter, the recording paper 6 is conveyed by the discharge roller pair 38 and 39 and discharged outside the apparatus. The fixing device 37 will be described later in detail. Here, the intermediate transfer belt unit 32 and the secondary transfer unit 50 correspond to an image transfer unit.

  The X, Y, and Z axes in FIG. 1 take the X axis in the transport direction (arrow A direction) when the recording paper 6 passes through the secondary transfer unit 50 and the fixing device 37, and the transport roller pair 35, The Y axis is taken in the direction of the rotation axis 36, and the Z axis is taken in a direction perpendicular to both the axes. Moreover, when each axis | shaft of X, Y, and Z is shown in the other figure mentioned later, these axial directions shall show a common direction. That is, the XYZ axes in each figure indicate the arrangement direction when the depiction portion of each figure constitutes the printer 1 shown in FIG. Here, it is assumed that the Z-axis is arranged in a substantially vertical direction.

  2 is an external perspective view of the fixing device 37. FIG. 3 is a front view of the fixing device 37 as viewed from the upstream side in the paper conveyance direction (arrow A direction). FIG. 4 is an external view of the fixing device 37. FIG. 5 is an external perspective view of the fixing device 37 with the outer cover removed, FIG. 6 is a right side view of the fixing device 37 with the outer cover removed, and FIG. 8 is a view of the AA cross section in FIG. 3 as viewed from the direction of the arrow. Note that there are cases where the front and rear, the left and right, and the up and down directions of the fixing device 37 are specified when the fixing device 37 shown in FIG.

  As shown in these drawings, the fixing device 37 is provided in a paper carry-in portion 101 to which the recording paper 6 is transported, an upper fixing unit 200 (FIG. 9) described later, and the fixing device provided in the upper fixing unit 200 as well. A fixing roller driving input gear 201 for receiving a rotational force for driving the roller 212 (FIG. 8) from the outside, a base unit 400 (FIG. 9) described later, and a cam mechanism provided in the base unit 400 are also driven. The cam drive input gear 401 and the handle 102 for receiving a driving force for the purpose from the outside are arranged so as to be in contact with the outside.

  When the fixing device 37 is mounted at a predetermined position inside the printing unit 3 as shown in FIG. 1, the fixing roller driving input gear 201 is connected to a not-shown fixing roller driving source connection gear provided inside the printing unit 3. The cam drive input gear 401 meshes with a connection gear (not shown) of a motor drive transmission system connected to a cam drive motor 611 (FIG. 26), which will be described later, provided in the printing unit 3. Receive driving force.

  FIG. 9 is an exploded side view showing the upper fixed unit 200, the lower movable unit 300, and the base unit 400 constituting the fixing device 37 in a state where they are separated from each other. FIG. 9A is a right side view of the upper fixed unit 200. FIG. 10B is a right side view of the lower movable unit 300, FIG. 10C is a right side view of the base unit 400, FIG. 10 is an external perspective view of the upper fixing unit 200, and FIG. FIG. 12 is a perspective view of the outer appearance of the upper fixing unit 200 with the drive transmission system sub-chassis 206 removed from the state of FIG. 9A. 13 is an external perspective view of the lower movable unit 300, FIG. 14 is an external perspective view of the base unit 400, FIG. 15 is a front view of the base unit 400, and FIG. The F-F cross section in 15 is a view from the arrow direction.

  As shown in the AA sectional view of FIG. 8, the fixing unit 37 extends in the left-right direction (hereinafter may be referred to as the longitudinal direction) and is disposed in the upper fixing unit 200. A pressure unit 310 (see FIG. 13) disposed in 210 and the lower movable unit 300 is incorporated.

  As with the pressure unit 310 shown in FIG. 13, the fixing unit 210 extends in the longitudinal direction at least in a region exceeding the width of the recording paper 6 to be passed, and is mainly used as an endless first belt. Fixing belt 211, a fixing roller 212 for moving and driving the fixing belt 211 in contact with the inner peripheral surface of the fixing belt 211, two guide rollers 217 and 218, and a guide member, and fixing in contact with the inner peripheral surface of the fixing belt 211. A roller guide member 213 that guides the inner peripheral surface of the belt 211, two heaters 214 that are disposed inside the fixing belt 211 and heat the fixing belt 211, a fixing pad 216 as a first pad, and a heater 214 A reflector 215 that reflects heat in a predetermined direction on the inner peripheral surface of the fixing belt 211 is provided.

  As shown in FIG. 13, the pressure unit 310 extends in the longitudinal direction at least in a region exceeding the width of the recording paper 6 to be passed, and is mainly a pressure belt as a second belt formed endlessly. 311, a pressure roller 312 that is driven by being in contact with the inner surface of the pressure belt 311 and pressure-contacting the fixing roller 212 as will be described later, and driving the pressure belt 311, two guide rollers 317 and 318, and a guide member A roller guide member 313 that contacts the inner surface of the pressure belt 311 and guides the inner peripheral surface of the pressure belt 311; a heater 314 that is disposed inside the pressure belt 311 and heats the pressure belt 311; A pressure pad 316 as a second pad and a reflector 315 that reflects heat from the heater 314 in a predetermined direction on the inner peripheral surface of the pressure belt 311 are provided.

  As will be described later, the pressure unit 310 moves up and down so as to come into contact with and separate from the fixing unit 210. As shown in FIG. 8, the nip position where the fixing roller 212 and the pressure roller 312 form a nip portion. The pressure pad 316 is also in pressure contact with the fixing pad 216, and the fixing belt 212 and the pressure roller 312, and the fixing belt 211 and the pressure belt 311 sandwiched between the fixing pad 216 and the pressure pad 316, respectively, are linear. The conveyance path is formed.

  In this state, when the fixing roller 212 obtains an external driving force and rotates in the direction of the arrow as will be described later, the fixing belt 211 and the pressure belt 311 are moved in the direction of the arrow together with the pressure roller 312 driven thereby. Rotate and move. In this state, when the recording paper 6 onto which the toner image has been transferred is conveyed to the joining portion of the fixing belt 211 and the pressure belt 311 via the paper carry-in portion 101, the fixing belt 211 and the heater 314 heated by the heater 214. The toner image is fixed on the recording paper 6 by the heating and pressurization that is sandwiched between the pressure belt 311 heated by the belt and further conveyed through the linear conveyance path. To 1).

(Upper fixed unit 200)
The upper fixing unit 200 in which the fixing unit 210 (FIG. 8) is disposed includes an upper chassis 203 and a left side chassis 204 joined to the upper chassis 203, as shown in FIGS. A main chassis 202 including a right side chassis 205 joined to an upper chassis 203 is provided. The left and right side chassis 204 and 205 are respectively provided with a rotation shaft 212 a of a fixing roller 212 of the fixing unit 210 and rotation shafts 217 a of guide rollers 217 and 218. , 218a are rotatably held at both ends. Then, left and right side chassis 204 and 205 are opposed to each other above the rear portion of the fixing roller 212 at a left engagement post 220 (not shown) and a right engagement post 221 (FIG. 12) that protrude toward the left and right, respectively. Is arranged.

  The right side chassis 205 fixes and holds the sub-chassis 206, and between the sub-chassis 206, the fixing roller driving input gear 201 and a first engaging with the fixing roller driving input gear 201 as shown in FIG. The intermediate gear 207 and the second intermediate gear 208 that meshes with the first intermediate gear 207 and the fixing roller gear 212b fixedly disposed on the rotation shaft 212a of the fixing roller 212 are rotatably held.

  With the above configuration, when the fixing roller driving input gear 201 is engaged with a connection gear of a fixing roller driving source (not shown) provided in the printing unit 3 (FIG. 1) and receives a rotational force in a predetermined direction, the rotation is performed. The force is transmitted to the rotation shaft 212a of the fixing roller 212 via the first and second intermediate gears 207 and 208, and rotates the fixing roller 212 in the counterclockwise arrow direction (FIG. 8).

(Lower movable unit 300)
The lower movable unit 300 provided with the pressure unit 310 (FIG. 8) includes a lower chassis 303, a left side chassis 304 joined to the lower chassis 303, and a lower chassis, as shown in FIGS. 303 includes a main chassis 302 composed of a right side chassis 305 joined to 303, and the left and right side chassis 304, 305 respectively rotate the rotation shafts 317a, 318a (FIG. 13) of the guide rollers 317, 318 of the pressure unit 310. Both ends of the rotary shaft 312a of the pressure roller 312 are held via left and right arms 306 and 307 as will be described later.

  FIG. 23 is an external perspective view of the pressure roller 312 and the left and right arms 306 and 307 that hold the pressure roller 312 as viewed obliquely from above.

  Here, the configuration in which the left and right side chassis 304 and 305 hold both ends of the rotation shaft 312a of the pressure roller 312 via the left arm 306 and the right arm 307, respectively, is intermediate between the left and right side chassis 304 and 305. Since the configuration is symmetrical with respect to a virtual center plane (perpendicular to the rotation axis 312a), only the configuration on the right side is shown here, and FIG. 9B, FIG. This will be described with reference to FIG.

  17 is a front view of the fixing device 37 with the exterior cover removed, and is a view of the BB cross section in FIG. 4 seen from the arrow direction. FIG. 18 is a cross-sectional view taken along the CC line in FIG. 19 is a view of the DD cross section in FIG. 4 as seen from the direction of the arrow, and FIG. 20 is a view of the EE cross section in FIG. 4 as seen from the direction of the arrow.

  The right side chassis 305 is provided with a rotating shaft 320 that is planted in the right direction from slightly above the rear, and the rotating shaft 320 is fitted into a shaft hole 307c (FIG. 23) of the right arm as an arm, and the right arm 307 is rotatably held. Similarly, the rotation shaft 319 of the left side chassis 304 is also fitted into the shaft hole 306c (FIG. 23) of the left arm 306 to hold the left arm 306 rotatably. As a result, the arms 306 and 307 can swing around the rotation shafts 319 and 320.

As shown in FIG. 19 and the like, the right arm 307 extends in the front-rear direction (X-axis direction), and is arranged in the vertical direction by a locking portion 307a formed by bending rightward at the front end side upper portion. The upper end side of the first spring 321 serving as the first urging member is locked. The lower end side of the first spring 321 is locked by a spring locking member 330 as a second restricting portion disposed in the right side chassis 305, and is kept in a compressed state.

For example, as shown in FIGS. 13 and 20, the right arm 307 forms a bearing 307 b (FIG. 23) near the rotation shaft 320 between the locking portion 307 a at the tip and the rotation shaft 320. One end side of the rotating shaft 312a of the pressure roller 312 is rotatably held by 307b, and the other end side of the rotating shaft 312a of the pressure roller 312 is rotated by the bearing 306b (FIG. 23) similarly formed on the left arm 306. Hold freely. Therefore, the pressure roller 312 is configured to be displaceable (slidable) with respect to the main chassis 302 by rotating the left and right arms 306 and 307. As will be described later, the restricting plate 341 as the first restricting portion comes into contact with the engaging portion 307 a of the right arm 307 urged by the first spring 321 and restricts the rotation of the right arm 307.

The pressure pad 316 (FIG. 8) extends in the longitudinal direction of the pressure unit 310 in substantially the same area as the pressure belt 311. FIG. 24 is an external perspective view of the pressure pad 316 and a pressure pad holder 332 as a pad holding member that holds the pressure pad 316. As shown in the figure, the pressure pad holder 332 includes a pad fixing portion 333 to which the pressure pad 316 is fixed, a left end portion 334 (FIG. 13) and a right end portion 335 formed at both ends of the pad fixing portion 333. Are integrally configured. The pressure pad holder 332 is held by the main chassis 302 so as to be slidable in the vertical direction.

  The upper surface portion 335a of the right end portion 335 is arranged in the vertical direction adjacent to the first spring 321 and locks the upper end side of the second spring 322. The lower end side of the second spring 322 is the right side chassis 305. It is locked by a spring locking member 330 disposed in the, and is kept in a compressed state.

  The left and right side chassis 304, 305 are formed with an upper left slit 304a and an upper right slit 305a, which are opened upward at opposite positions above the rear part, respectively, and at the lower opposed positions, the lower part is opened. A lower left front slit 304b, a lower right front slit 305b as a first guide groove, a lower left rear slit 304c, and a lower right rear slit 305c as a second guide groove are formed.

(Base unit 400)
The base unit 400 provided with the cam mechanism includes a base chassis 402 extending in the left-right direction (longitudinal direction) as shown in FIGS. 9C and 14 to 17. The base chassis 402 has a pair of support plates 402 a and 402 b that rotatably hold the first cam shaft 403 at both ends in the longitudinal direction, and a second that is disposed adjacent to and parallel to the first cam shaft 403. A pair of support plates 402c and 402d are formed to hold the cam shaft 404 rotatably.

  The first cam shaft 403 has a cam 411 and a cam gear 413 as a first cam fixedly arranged at the left end, and a cam 412 and a cam gear 414 as a first cam fixed and arranged at the right end. In the second cam shaft 404, a cam 421 and a cam gear 423 as a second cam are coaxially fixedly arranged at the left end, and a cam 422 and a cam gear 424 as a second cam are coaxially fixed at the right end. The cam gear 413 and the cam gear 423, and the cam gear 414 and the cam gear 424 are disposed so as to mesh with each other at both ends.

  The base chassis 402 is formed with screw holes 402e and 402f for screwing a holding plate 430 that rotatably holds the cam drive input gear 401 as shown in FIG. A holding plate 430 is fixedly disposed by screwing so that the input gear 401 meshes with the cam gear 414.

  As shown in FIG. 16, the cams 412 and 422 have a shape that is plane-symmetric with respect to a virtual center plane intermediate between the first cam shaft 403 and the second cam shaft 404 and are arranged. The cam 411 is disposed on the first cam shaft 403 with the same shape and the same angle as the cam 412, and the cam 421 is disposed on the second cam shaft 404 with the same shape and the same angle as the cam 422.

  Next, the attachment relationship of the upper fixed unit 200, the lower movable unit 300, and the base unit 400 will be described.

  When the lower movable unit 300 is attached to the base unit 400, on the right side of the fixing device 37, the first lower portion of the base unit 400 is inserted into the lower right front slit 305b formed in the right side chassis 305 as shown in FIG. The cam shaft 403 is slidably fitted, and similarly, the second cam shaft 404 of the base unit 400 is slidably fitted into the lower right rear slit 305c (see FIG. 18), and further the cam of the first cam shaft 403 412 abuts on a contact projection plate 305d as a first engagement portion formed at the upper part of the lower right front slit 305b, and the cam 422 of the second cam shaft 404 is formed at the upper part of the lower right rear slit 305c. It mounts | wears so that it may contact | abut to the contact protrusion board 305e as the made 2nd engaging part (refer FIG. 19).

  At this time, also on the left side of the fixing device 37, the first cam shaft 403 of the base unit 400 is slidably fitted into the lower left front slit 304b formed in the left side chassis 304 (FIG. 13), and similarly the lower left rear slit 304c. The second cam shaft 404 of the base unit 400 is slidably fitted, and the cam 411 of the first cam shaft 403 is further formed on the abutting protrusion plate 304d (see FIG. (Not shown), and the cam 421 of the second cam shaft 404 comes into contact with a contact projection plate 304e (not shown) formed on the upper part of the lower left rear slit 304c.

  Next, the upper fixing unit 200 is fixed to the base unit 400. At this time, on the right side of the fixing device 37, the right engagement post 221 disposed on the right side chassis 205 of the upper fixing unit 200 (see FIG. 12). Is inserted into the upper right slit 305a formed in the lower movable unit 300, and the left engagement post 220 disposed on the left side chassis 204 of the upper fixed unit 200 is also movable on the lower side of the fixing device 37. It arrange | positions so that it may fit in the upper left slit 304a (refer FIG. 13) formed in the unit.

  Then, as shown in FIG. 9, a mounting hole 205a formed in the lower part of the right side chassis 205 and a screw groove 402g formed in the base chassis 402 of the base unit 400 so as to face the mounting hole 205a are set with a set screw 501. And the upper fixing unit 200 is fixed to the base unit 400. Note that the upper fixing unit 200 is fixed by the set screw 501 at other locations, for example, a mounting hole 204a (FIG. 10) formed in the lower portion of the left side chassis 204 and a screw groove 402h (FIG. 14) formed in the base chassis 402. ), Etc., etc., etc.

  With the above configuration, the lower movable unit 300 is engaged with the first cam shaft 403 and the second cam shaft 404 of the base unit 400 and the upper fixed unit 200 on the right side of the fixing device 37 as shown in FIG. Guided by the post 221, and on the left side of the fixing device 37, the first cam shaft 403 and the second cam shaft 404 of the base unit 400 and the left engagement post 220 (not shown) of the upper fixing unit 200 are also guided. Thus, it is held so as to be movable in the vertical direction, and is further moved in the vertical direction by the rotation of the four left and right cams 411, 412, 421, 422.

  Here, the base chassis 402 of the base unit 400, the first and second cam shafts 403 and 404, and the upper fixed unit 200 fixed to the base chassis 402 correspond to the first unit. The lower movable unit 300 that is held movably by the second unit corresponds to the second unit, and includes cams 411, 412, 421, 422, first and second cam shafts 403, 404, cam gears 413, 414, 423, 424, The cam drive input gear 401 and the holding plate 430 correspond to a moving mechanism. Among these, the cam gears 413, 414, 423, 424, the cam drive input gear 401, and the holding plate 430 correspond to a drive transmission system.

  The cam mechanisms for moving the lower movable unit 300 up and down disposed on the left and right sides of the fixing device 37 are the left and right side chassis 304 except for the holding plate 430 that rotatably holds the cam drive input gear 401. , 305 is configured symmetrically with respect to a virtual center plane (perpendicular to the camshafts 403 and 404), and the operation is the same. Will be explained.

(Description of operation)
The first cam shaft 403 and the second cam shaft 404 are a motor drive transmission system in which the cam drive input gear 401 is connected to a cam drive motor 611 (FIG. 26) described later provided in the printing unit 3 (FIG. 1). When the rotational force in the predetermined direction is received by meshing with the connection gear that is not connected, the rotational force is transmitted to the first cam shaft 403 and the second cam shaft 404 via the cam gears 414 and 424, and for example, the cam 412 shown in FIG. And the cam 422 rotate in opposite directions at the same speed.

  17 and 20 show a state in which the lower movable unit 300 (see FIG. 9) is slid to the uppermost position by the cam mechanism. At this time, the pressure roller 312 presses the fixing roller 212 as shown in FIG. A nip is formed. At this time, since the locking portion 307a and the regulating plate 341 are separated from each other, and the lower end surface 335b and the spring locking member 330 are separated from each other, the urging force of the first spring 321 is exerted on the nip portion, and the second spring 322 is attached. A force can be exerted on the pressure pad 316.

  On the other hand, FIG. 21 is a front view of the fixing device 37 with the exterior cover removed, and is a view of the BB cross section in FIG. 4 viewed from the arrow direction, and the lower movable unit 300 (see FIG. 9) is moved by the cam mechanism. FIG. 22 is a view of the EE cross section in FIG. 4 seen from the direction of the arrow, and the lower movable unit 300 (see FIG. 9) is slid to the lowest position by the cam mechanism. Indicates. At this time, the pressure unit 310 is separated from the fixing unit 210 as shown in FIG.

  Hereinafter, the operation of each part when the lower movable unit 300 slides between the uppermost and lowermost positions will be described. The drawings other than FIG. 21 and FIG. 22 all show the state when the lower movable unit 300 is positioned at the top for convenience.

  For example, as shown in FIG. 19, the contact protrusion plates 305 d and 305 e of the lower movable unit 300 always keep in contact with the peripheral surfaces of the cams 412 and 422 due to the weight of the lower movable unit 300. Therefore, when the cams 412 and 422 are in the rotation position as shown in FIG. 22 where these contact positions are at the lowest position, the lower movable unit 300 reaches the lowest position. Hereinafter, this lowest position of the lower movable unit 300 may be referred to as a separated position.

  At this time, the right arm 307 is urged clockwise by the first spring 321 (FIG. 22), but the right arm 307 is pivoted in the same direction in a state where the locking portion 307a at the tip is pressed against the restriction plate 341. It is regulated. The rotation position of the right arm 307 at this time may be hereinafter referred to as an initial rotation position.

  On the other hand, the upper end 335 a of the right end 335 of the pressure pad holder 332 (FIG. 8) is urged upward by the second spring 322, but the lower surface 335 b is in contact with the lower surface of the spring locking member 330. The movement in the same direction is restricted. The movement position of the pressure pad holder 332 at this time may be hereinafter referred to as an initial movement position.

  FIG. 21 is a view of the BB cross section in FIG. 4 as viewed from the direction of the arrow when the lower movable unit 300 is in the separated position. As shown in the figure, the pressure unit 310 disposed in the lower movable unit 300 is in a state of being separated from the fixing unit 210 disposed in the upper fixed unit 200 (see FIG. 9). At this time, the uppermost portion of the pressure roller 312 that is rotatably held by the right arm 307 at the initial rotation position, and the uppermost portion of the pressure pad 316 that is held by the pressure pad holder 332 at the initial movement position. Are set to have substantially the same height, and support the pressure belt 311.

  21 and 22 in which the lower movable unit 300 is in the separated position, when the cam drive input gear 401 is rotationally driven, for example, in the direction of arrow C (FIG. 5), the cam 412 and the cam 422 have different arrow directions (see FIG. 22), the contact projection plates 305d and 305e, that is, the lower movable unit 300 are gradually pushed upward. Accordingly, for example, the pressure unit 310 shown in FIG. 21 moves upward and eventually presses the fixing unit 210 provided in the upper fixing unit 200. That is, the pressure roller 312 and the pressure pad 316 of the pressure unit 310 abut on the fixing roller 212 and the fixing pad 216 via the pressure belt 311 and the fixing belt 211, respectively.

  When the lower movable unit 300 is further pushed up by the rotation of the cam 412 and the cam 422, the pressure roller 312 comes into pressure contact with the fixing roller 212 and the pressure pad 316 comes into pressure contact with the fixing pad 216, but both stop moving upward. Accordingly, for example, the right arm 307 and its locking portion 307a shown in FIG. 20, and the pressure pad holder 332 (FIG. 17) and its right end 335 stop at the position shown in FIG. Goes up further.

  As a result, the right end 335 of the pressure pad holder 332 moves downward from the initial movement position relative to the right side chassis 305, and the lower surface portion 335b is separated from the lower surface of the spring locking member 330. The right arm 307 rotates in the counterclockwise direction from the initial rotation position relative to the right side chassis 305 so that the engaging portion 307a is separated from the restricting plate 341. The upper position indicated by 20 is reached and the upward movement is stopped. Hereinafter, this uppermost position of the lower movable unit 300 may be referred to as a nip position.

  Therefore, when the lower movable unit 300 is in the nip position shown in FIGS. 17 and 20, the pressure roller 312 is further urged by the first spring 321 that has been further compressed and increased in urging force, and thus the pressure belt. 311 and the fixing belt 211 are pressed through the fixing belt 211 to form a desired nip portion, and the pressure pad 316 is further urged by the second spring 322 having increased urging force and pressurized. The belt 311 and the fixing belt 211 are pressed against the fixing pad 216 with a predetermined pressing force.

  As described above, when the lower movable unit 300 is in the nip position, the pressure roller 312 and the pressure pad 316 are urged by separate springs independently from each other, and accordingly, urging force suitable for each is individually applied. Can contribute to stabilization of the fixing process.

  When the cam drive input gear 401 is further rotationally driven in the direction of arrow C (FIG. 5) from the state where the lower movable unit 300 is in this nip position, the cam 412 and the cam 422 have the same speed in different arrow directions (FIG. 22). The contact protrusion plates 305d and 305e that contact with each other, that is, the lower movable unit 300 are gradually lowered.

  Accordingly, the right end 335 of the pressure pad holder 332 moves upward toward the initial movement position relative to the right side chassis 305, and the lower surface 35b abuts against the lower surface of the spring locking member 330, The right arm 307 rotates in the clockwise direction toward the initial rotation position relative to the right side chassis 305, and the locking portion 307a comes into contact with the restriction plate 341.

  During this time, the nip formed between the pressure roller 312 and the fixing roller 212 is eliminated, and the pressing of the pressure belt 311 and the fixing belt 211 to the fixing pad 216 by the pressure pad 316 is eliminated.

  Thereafter, the lower movable unit 300 moves down integrally, and eventually reaches the lowest position (separated position) shown in FIGS. 21 and 22 and stops moving downward.

  Here, the first cam shaft 403 and the second cam shaft are parallel to the plane including the first cam shaft 403 and the second cam shaft 404 and orthogonal to these cam shafts (X-axis direction). Between 404, the rotating shaft 312a of the pressure roller 312 when in the nip position is located. As a result, the urging of the fixing roller 212 by the pressure roller 312 can be performed stably.

  Further, in the direction perpendicular to the plane including the first cam shaft 403 and the second cam shaft 404 (Z-axis direction), between the rotation shaft 312a of the pressure roller 312 and the lower right front slit 305b when in the nip position. The abutting projection plate 305d is located at the nip position, and the abutting projection plate 305e is located between the rotation shaft 312a of the pressure roller 312 and the lower right rear slit 305c. Thereby, the slide movement of the lower movable unit 300 can be performed stably.

  The biasing force of the first spring 321 at the separation position is smaller than the biasing force of the first spring 321 at the nip position, and the biasing force of the second spring 322 at the separation position is the biasing force of the second spring 322 at the nip position. Since the force is smaller than the force, the strength of the restriction plate 341 that receives the biasing force of the first spring 321 at the separated position and the strength of the left and right end portions 344 and 345 of the pressure pad holder 332 that receives the biasing force of the second spring 322 at the spaced position. Can be reduced.

(Position detection mechanism)
Next, a position detection mechanism of the lower movable unit 300 that slides in the vertical direction with respect to the integrated upper fixed unit 200 and base unit 400 will be described. FIG. 25 is a block diagram schematically showing this position detection mechanism.

  In the base unit 400, a position detection arm 450 that abuts on an engagement portion 305f (see FIG. 9B) of the right side chassis 305 of the lower movable unit 300 that slides in the vertical direction is rotatably held. . The detection arm 450 is formed in a square shape and is rotatably held by the base unit 400 with its refracting portion serving as a rotation shaft 450a. One end of the detection arm 450 abuts on the engagement portion 305f of the right side chassis 305, and the like. A detected portion 450b is disposed at the end. It is assumed that the position detection arm 450 generates a force that rotates clockwise in a required rotation range due to its own weight.

  The detector 460 is disposed in the base unit 400 and detects the detected portion 450b of the position detection arm 450 at the detection position 460a. As shown by the solid line in FIG. When the position reaches the nip position, the position detection arm 450 is positioned so as to detect the detected portion 450b. Accordingly, the detector 460 detects when the lower movable unit 300 reaches the uppermost nip position, and outputs the detected information to the image formation control unit 600 (FIG. 26) described later.

(Cam drive motor control)
FIG. 26 is a block diagram illustrating a configuration of a main part of a control system that is disposed inside the printer 1 and controls the main operation of the printer 1.

  In the figure, an image forming control unit 600 includes a processor 601, a ROM 602, a RAM 603, input / output ports 604 and 605, a counter, a timer, and the like. Sequence control and print operation are performed. Note that description of these operations is omitted here.

  The control unit 600 also receives detection information from the detector 460 described above, and outputs an instruction signal to the cam drive motor control unit 610 that controls the drive of the cam drive motor 611 based on this information.

  The cam drive motor 611 is disposed inside the printing unit 3 (FIG. 1), and meshes with the cam drive input gear 401 of the fixing device 37 that is also mounted inside the printing unit 3 via a motor drive transmission system (not shown). Then, the cam drive input gear 401 is rotationally driven in the direction of arrow C (FIG. 5).

  Here, the image formation control unit 600 rotates the cam drive motor 611 so as to move the lower movable unit 300 of the fixing device 37 to the uppermost nip position, for example, during conveyance of the recording paper 6 accompanying the printing operation. When an instruction is given to the cam drive motor control unit 610 and detection information indicating that the lower movable unit 300 has reached the nip position is received from the detector 460, a rotation stop instruction is issued. Thus, the lower movable unit 300 can be maintained at the nip position shown in FIG. 17, for example.

  In the motor drive transmission system from the cam drive motor 611 to the cam drive input gear 401, the first and second cam shafts 403 are provided when the cam drive motor 611 is stopped, for example, by interposing a worm gear. , 403 are prevented from rotating by a load.

  On the other hand, the image forming control unit 600 drives the cam drive motor 611 by a predetermined amount to move the lower movable unit 300 of the fixing device 37 to the lowest position, for example, when the recording paper 6 is not transported when printing is stopped. The cam drive motor control unit 610 is instructed to do so. Here, the cams 412 and 422 rotate by a predetermined rotation angle from the rotational position where the lower movable unit 300 is maintained at the nip position as shown in FIG. 20 to the rotational position where it is maintained at the separated position shown in FIG. As described above, the rotation speed or drive time of the cam drive motor 611 is set in advance, and the cam drive motor 611 is driven by this set amount. Here, the detector 460, the image formation control unit 600, the cam drive motor control unit 610, and the cam drive motor 611 correspond to the drive control unit.

  In the above configuration, the image formation control unit 600 repeats the position movement of the lower movable unit 300 to the nip position / separation position in accordance with the operation / stop of the printing operation of the printer 1.

  In the present embodiment, the roll paper 5 is cut and printed on the recording paper 6. However, the present invention is not limited to this, and the roll paper 5 may be printed as it is. It can take the form.

  As described above, according to the printer 1 of the first embodiment, the pressure unit 310 can be moved to the nip position and the separation position with respect to the fixing unit 210 of the fixing device 37. At times, the fixing unit 210 and the pressure unit 310 can avoid an undesirable situation of leaving the recording paper 6 or the roll paper 5 sandwiched therebetween.

  In the above description of the embodiment, the words “up”, “down”, “left”, “right”, “front”, “rear” are used for convenience, and the fixing device. There is no limitation on the absolute positional relationship in the state of arranging the.

  In the above embodiments, the present invention has been described using an example in which the present invention is applied to an electrophotographic and secondary transfer type color printer. However, the present invention is not limited to this, and the present invention is not limited thereto. Peripheral), and also applicable to a primary transfer type color printer, a single color printer, and the like.

DESCRIPTION OF SYMBOLS 1 Printer, 2 Introduction guide part, 3 Printing part, 4 Paper holder, 5 Roll paper, 6 Recording paper, 21 Guide roller, 22 Feed roller pair, 23 Paper cutting part, 24 Paper sensor, 30 Image formation part, 31 Process unit , 32 intermediate transfer belt unit, 33 photosensitive drum, 34 secondary transfer roller, 35 transport roller pair, 36 transport roller pair, 37 fixing device, 38 discharge roller pair, 39 discharge roller pair, 40 write sensor, 41 intermediate Transfer belt, 42 drive roller, 43 tension roller, 44 secondary transfer backup roller, 45 primary transfer roller, 50 secondary transfer unit, 101 paper carry-in unit, 102 handle, 200 upper fixing unit, 201 fixing roller drive input gear, 202 Mei Chassis, 203 Upper chassis, 204 Left side chassis, 204a Mounting hole, 205 Right side chassis, 205a Mounting hole, 206 Subchassis, 207 First intermediate gear, 208 Second intermediate gear, 210 Fixing unit, 211 Fixing belt, 212 Fixing Roller, 212a Rotating shaft, 212b Fixing roller gear, 213 Roller guide member, 214 Heater, 215 Reflector, 216 Fixing pad, 217 Guide roller, 217a Rotating shaft, 218 Guide roller, 218a Rotating shaft, 221 Right engagement post, 300 Lower movable Unit 302 Main chassis 303 Lower chassis 304 Left side chassis 304a Upper left slit 305 Right side chassis 305a Right Upper slit, 305b Lower right front slit, 305c Lower right rear slit, 305d Contact projection plate, 305e Contact projection plate, 305f Engagement portion, 306 Left arm, 306a Locking portion, 306b Bearing, 306c Shaft hole, 307 Right arm, 307a locking portion, 307b bearing, 307c shaft hole, 310 pressure unit, 311 pressure belt, 312 pressure roller, 312a rotating shaft, 313 roller guide member, 314 heater, 315 reflector, 316 pressure pad, 317 Guide roller, 317a Rotating shaft, 318 Guide roller, 318a Rotating shaft, 319, 320 Rotating shaft, 321 First spring, 322 Second spring, 330 Spring locking member, 332 Pressure pad holder, 333 Head fixing portion, 334 left end portion, 335 right end portion, 335a upper surface portion, 335b lower surface portion, 341 regulating plate, 400 base unit, 401 cam drive input gear, 402 base chassis, 402a support plate, 402b support plate, 402c support plate 402d support plate, 402e screw hole, 402f screw hole, 402g screw groove, 402h screw groove, 403 first cam shaft, 404 second cam shaft, 411 cam, 412 cam, 413 cam gear, 414 cam gear, 421 cam, 422 cam , 423 cam gear, 424 cam gear, 430 holding plate, 450 detection arm, 450a rotating shaft, 450b detected portion, 460 detector, 460a detection position, 501 set screw, 6 0 image forming control unit, 601 a processor, 602 ROM, 603 RAM, 604 an input port, 605 output ports, 610 cam drive motor control unit, 611 cam driving motor.

Claims (11)

A first unit;
A second unit movably disposed with respect to the first unit;
A moving mechanism for sliding the second unit to a first position and a second position with respect to the first unit;
The first unit is:
An endless first belt;
A fixing roller rotatably held around a rotation axis whose position is fixed inside the first belt;
The second unit is
An endless second belt;
A pressure roller held rotatably about a rotation axis displaceable inside the second belt;
A first urging member that urges the pressure roller toward the fixing roller;
The pressure roller is urged by the first urging member at the first position to press the fixing roller via the first belt and the second belt, and the second roller A fixing device that is separated from the fixing roller at a position. A first unit;
A second unit movably disposed with respect to the first unit;
A moving mechanism that moves the second unit to a first position and a second position with respect to the first unit;
The first unit is:
An endless first belt;
A fixing roller rotatably held around a rotation axis whose position is fixed inside the first belt;
The second unit is
An endless second belt;
A pressure roller held rotatably about a rotation axis displaceable inside the second belt;
A first urging member that urges the pressure roller toward the fixing roller;
The pressure roller is urged by the first urging member at the first position to press the fixing roller via the first belt and the second belt, and the second roller At a position separated from the fixing roller ,
The moving mechanism is
A first cam shaft and a second cam shaft which are arranged in parallel with each other and are rotatably held;
A first cam fixed to the first cam shaft and a second cam fixed to the second cam shaft;
A drive transmission system for transmitting a driving force to the first cam shaft and the second cam shaft;
Have
The second unit is
A first engagement portion that engages with the peripheral surface of the first cam and a second engagement portion that engages with the peripheral surface of the second cam;
A first guide groove guided by the first cam shaft and a second guide groove guided by the second cam shaft;
A fixing device for, characterized in that have a. A first unit;
A second unit movably disposed with respect to the first unit;
A moving mechanism that moves the second unit to a first position and a second position with respect to the first unit;
The first unit is:
An endless first belt;
A fixing roller rotatably held around a rotation axis whose position is fixed inside the first belt ;
A first pad fixed to the inside of the first belt ;
The second unit is
An endless second belt;
A pressure roller held rotatably about a rotation axis displaceable inside the second belt;
A second pad movable inside the second belt ;
A first urging member that urges the pressure roller toward the fixing roller ;
A second biasing member that biases the second pad toward the first pad ;
The pressure roller is urged by the first urging member at the first position to press the fixing roller via the first belt and the second belt, and the second roller At a position separated from the fixing roller ,
The second pad is urged by the second urging member at the first position and is pressed against the first pad via the first belt and the second belt, A fixing device , wherein the fixing device is separated from the first pad at a second position . The first biasing member is a compression spring, and the biasing force of the first biasing member when in the second position is the first biasing member when in the first position. The fixing device according to claim 1 , wherein the fixing device is smaller than the urging force. The second unit includes an arm rotatably held,
The arm holds the pressure roller rotatably around a rotation axis parallel to the rotation axis of the arm, and the first biasing member is disposed on the opposite side of the rotation axis via the rotation axis. The fixing device according to claim 4 , wherein the fixing device is subjected to an urging force. A first unit;
A second unit movably disposed with respect to the first unit;
A moving mechanism that moves the second unit to a first position and a second position with respect to the first unit;
The first unit is:
An endless first belt;
A fixing roller rotatably held around a rotation axis whose position is fixed inside the first belt;
The second unit is
An endless second belt;
A pressure roller held rotatably about a rotation axis displaceable inside the second belt;
A first urging member that urges the pressure roller toward the fixing roller ;
An arm held rotatably ,
The pressure roller is urged by the first urging member at the first position to press the fixing roller via the first belt and the second belt, and the second roller At a position separated from the fixing roller ,
The first biasing member is a compression spring, and the biasing force of the first biasing member when in the second position is the first biasing member when in the first position. Smaller than the biasing force of
The arm holds the pressure roller rotatably around a rotation axis parallel to the rotation axis of the arm, and exerts an urging force by the compression spring on the opposite side of the rotation axis via the rotation axis. received,
The moving mechanism is
A first cam shaft and a second cam shaft which are arranged in parallel with each other and are rotatably held;
A first cam fixed to the first cam shaft and a second cam fixed to the second cam shaft;
A drive transmission system for transmitting a driving force to the first cam shaft and the second cam shaft;
Have
The second unit is
A first engagement portion that engages with the peripheral surface of the first cam and a second engagement portion that engages with the peripheral surface of the second cam;
A first guide groove guided by the first cam shaft and a second guide groove guided by the second cam shaft;
Have
In a direction parallel to a plane including the first cam shaft and the second cam shaft and orthogonal to the first cam shaft, between the first cam shaft and the second cam shaft, The fixing device , wherein a rotation shaft of the pressure roller is located at the first position . A first unit;
A second unit movably disposed with respect to the first unit;
A moving mechanism that moves the second unit to a first position and a second position with respect to the first unit;
The first unit is:
An endless first belt;
A fixing roller rotatably held around a rotation axis whose position is fixed inside the first belt;
The second unit is
An endless second belt;
A pressure roller held rotatably about a rotation axis displaceable inside the second belt;
A first urging member that urges the pressure roller toward the fixing roller ;
An arm held rotatably ,
The pressure roller is urged by the first urging member at the first position to press the fixing roller via the first belt and the second belt, and the second roller At a position separated from the fixing roller ,
The first biasing member is a compression spring, and the biasing force of the first biasing member when in the second position is the first biasing member when in the first position. Smaller than the biasing force of
The arm holds the pressure roller rotatably around a rotation axis parallel to the rotation axis of the arm, and exerts an urging force by the compression spring on the opposite side of the rotation axis via the rotation axis. received,
The moving mechanism is
A first cam shaft and a second cam shaft which are arranged in parallel with each other and are rotatably held;
A first cam fixed to the first cam shaft and a second cam fixed to the second cam shaft;
A drive transmission system for transmitting a driving force to the first cam shaft and the second cam shaft;
Have
The second unit is
A first engagement portion that engages with the peripheral surface of the first cam and a second engagement portion that engages with the peripheral surface of the second cam;
A first guide groove guided by the first cam shaft and a second guide groove guided by the second cam shaft;
Have
In a direction perpendicular to a plane including the first cam shaft and the second cam shaft, the rotation shaft of the pressure roller and the first guide groove when in the first position are between the first guide groove and the first guide groove. The first engagement portion is located, and the second engagement portion is located between the rotation shaft of the pressure roller and the second guide groove when the first engagement portion is in the first position. A fixing device. The second urging member is a compression spring, and the urging force of the second urging member when in the second position is the second urging member when in the first position. The fixing device according to claim 3 , wherein the fixing device is smaller than the urging force. A first unit;
A second unit movably disposed with respect to the first unit;
A moving mechanism that moves the second unit to a first position and a second position with respect to the first unit;
The first unit is:
An endless first belt;
A fixing roller rotatably held around a rotation axis whose position is fixed inside the first belt;
The second unit is
An endless second belt;
A pressure roller held rotatably about a rotation axis displaceable inside the second belt;
A first urging member that urges the pressure roller toward the fixing roller ;
An arm that supports the pressure roller so as to be displaceable in the direction of the fixing roller;
A first restricting portion for restricting displacement of the arm in a direction in which the pressure roller is directed toward the fixing roller ;
The pressure roller is urged by the first urging member at the first position to press the fixing roller via the first belt and the second belt, and the second roller At a position separated from the fixing roller ,
The first biasing member is arranged to bias the arm toward the first restricting portion,
When the second unit is in the first position, the arm is separated from the first restricting portion, and the pressure roller is moved by the urging force of the first urging member. 2 pressing the fixing roller through the belt 2;
When the second unit is in the second position, the pressure roller is separated from the fixing roller, and the arm contacts the first restricting portion by the urging force of the first urging member. a fixing device which is characterized in that contact. The second unit includes a pad holding member that holds the second pad so that the second pad can be displaced in the direction of the first pad, and the second pad includes the first pad. A second restricting portion for restricting the displacement of the pad holding member in a direction toward the pad.
The second urging member is arranged to urge the pad holding member toward the second restricting portion,
When the second unit is in the first position, the pad holding member is separated from the second restricting portion, and the second pad is moved by the urging force of the second urging member. Pressing the first pad through the belt and the second belt,
When the second unit is in the second position, the second pad is separated from the first pad, and the pad holding member is moved by the urging force of the second urging member. The fixing device according to claim 3 , wherein the fixing device abuts against the restriction portion. An image forming unit for forming a developer image;
An image transfer portion for transferring the developer image to a recording medium;
A fixing device according to any one of claims 1 to 10,
A drive control unit that drives and controls movement of the second unit;
The drive control unit moves the second unit to the second position during non-image formation when the image forming unit does not form the developer image.

Images